ROS2 Driver Observe#

What you’ll do

ROS2 cmd_vel을 받아 setCommand(v, omega)를 업데이트합니다.
Driver 수신 큐를 처리해 vehicle_speed, battery_voltage 토픽을 발행합니다.
마지막 명령을 주기적으로 재전송할 수 있습니다.

Prerequisites

ROS2 환경
ROS2 Driver Demo

Next

이 튜토리얼은 driver_observe 예제를 ROS2 노드로 옮겨, 속도/배터리를 토픽으로 발행하는 구조를 단계별로 만들고 이해하는 데 집중합니다.

목표#

ROS2 노드에서 Driver 시작
/cmd_vel을 구독해 setCommand(v, omega) 업데이트
Driver 수신 큐를 drain 해서 /vehicle_speed, /battery_voltage 발행
마지막 명령을 주기적으로 재전송 (선택)

단계별 구현 가이드#

단계 1) include 준비#

#include "KMC_driver.hpp"

#include <rclcpp/rclcpp.hpp>
#include <geometry_msgs/msg/twist.hpp>
#include <std_msgs/msg/float32.hpp>

#include <chrono>
#include <optional>
#include <string>

단계 2) 노드 클래스 뼈대#

class KmcHardwareDriverObserveNode final : public rclcpp::Node {
public:
  KmcHardwareDriverObserveNode() : Node("kmc_hardware_driver_observe_node") {
    // 다음 단계에서 파라미터/Driver 설정을 채운다.
  }

  ~KmcHardwareDriverObserveNode() override { driver_.stop(); }

private:
  KMC_HARDWARE::Driver driver_;
};

단계 3) 멤버 변수 준비#

  rclcpp::Publisher<std_msgs::msg::Float32>::SharedPtr speed_pub_;
  rclcpp::Publisher<std_msgs::msg::Float32>::SharedPtr battery_pub_;
  rclcpp::Subscription<geometry_msgs::msg::Twist>::SharedPtr cmd_sub_;
  rclcpp::TimerBase::SharedPtr rx_timer_;
  rclcpp::TimerBase::SharedPtr cmd_timer_;

  std::string port_;
  int baud_{921600};
  double control_rate_hz_{100.0};
  double vehicle_speed_rate_hz_{50.0};
  int command_timeout_ms_{200};
  double command_refresh_hz_{50.0};
  int realtime_priority_{-1};
  int cpu_affinity_{-1};
  double battery_hz_{1.0};

  float last_cmd_v_{0.0f};
  float last_cmd_w_{0.0f};
  std::optional<rclcpp::Time> last_cmd_received_;

단계 4) 파라미터 선언#

    port_ = declare_parameter<std::string>("port", "/dev/ttyKMC");
    baud_ = declare_parameter<int>("baud", 921600);
    control_rate_hz_ = declare_parameter<double>("control_rate_hz", 100.0);
    vehicle_speed_rate_hz_ = declare_parameter<double>("vehicle_speed_rate_hz", 50.0);
    command_timeout_ms_ = declare_parameter<int>("command_timeout_ms", 200);
    command_refresh_hz_ = declare_parameter<double>("command_refresh_hz", 50.0);
    realtime_priority_ = declare_parameter<int>("realtime_priority", -1);
    cpu_affinity_ = declare_parameter<int>("cpu_affinity", -1);
    battery_hz_ = declare_parameter<double>("battery_hz", 1.0);

단계 5) Driver 옵션 구성 + 시작#

배터리 요청 주기(battery_hz)도 옵션에 반영합니다. 옵션 필드 의미는 Driver::Options를 기준으로 합니다.

    KMC_HARDWARE::Driver::Options opt;
    opt.port = port_;
    opt.serial.baudrate = baud_;
    opt.serial.hw_flow_control = true;
    opt.control_rate_hz = control_rate_hz_;
    opt.vehicle_speed_rate_hz = vehicle_speed_rate_hz_;
    opt.command_timeout_ms = command_timeout_ms_;
    opt.realtime_priority = realtime_priority_;
    opt.cpu_affinity = cpu_affinity_;

    opt.poll_battery = battery_hz_ > 0.0;
    opt.battery_rate_hz = battery_hz_ > 0.0 ? battery_hz_ : 1.0;

    if (!driver_.start(opt)) {
      throw std::runtime_error("Failed to open UART port: " + port_);
    }

단계 6) 토픽 구성#

속도와 배터리 토픽을 발행할 퍼블리셔를 만들고, /cmd_vel을 구독해 setCommand()로 전달합니다.

    speed_pub_ = create_publisher<std_msgs::msg::Float32>("vehicle_speed", 10);
    battery_pub_ = create_publisher<std_msgs::msg::Float32>("battery_voltage", 10);

    cmd_sub_ = create_subscription<geometry_msgs::msg::Twist>(
        "cmd_vel", 10, [this](geometry_msgs::msg::Twist::SharedPtr msg) {
          const float v = static_cast<float>(msg->linear.x);
          const float w = static_cast<float>(msg->angular.z);
          last_cmd_v_ = v;
          last_cmd_w_ = w;
          last_cmd_received_ = now();
          driver_.setCommand(v, w);
        });

단계 7) 수신 큐 drain 함수#

Driver의 수신 큐에서 메시지를 꺼내서 종류별로 publish 합니다.

  void drainDriverQueue() {
    for (int i = 0; i < 100; ++i) {
      auto msg = driver_.tryPopMessage();
      if (!msg) break;

      if (auto* vs = std::get_if<KMC_HARDWARE::VehicleSpeed>(&*msg)) {
        std_msgs::msg::Float32 out;
        out.data = vs->mps;
        speed_pub_->publish(out);
      } else if (auto* bv = std::get_if<KMC_HARDWARE::BatteryVoltage>(&*msg)) {
        std_msgs::msg::Float32 out;
        out.data = bv->volt;
        battery_pub_->publish(out);
      }
    }
  }

단계 8) drain 타이머 + 명령 재전송 타이머#

수신 큐는 짧은 주기로 돌리고, 명령은 마지막 값을 주기적으로 업데이트합니다.

    using namespace std::chrono_literals;
    rx_timer_ = create_wall_timer(1ms, [this]() { drainDriverQueue(); });

    if (command_refresh_hz_ > 0.0) {
      const auto period = std::chrono::duration_cast<std::chrono::nanoseconds>(
          std::chrono::duration<double>(1.0 / command_refresh_hz_));
      cmd_timer_ = create_wall_timer(period, [this]() {
        if (!last_cmd_received_.has_value()) return;
        driver_.setCommand(last_cmd_v_, last_cmd_w_);
      });
    }

단계 9) main 함수#

int main(int argc, char** argv) {
  rclcpp::init(argc, argv);
  try {
    auto node = std::make_shared<KmcHardwareDriverObserveNode>();
    rclcpp::spin(node);
  } catch (const std::exception& e) {
    RCLCPP_ERROR(rclcpp::get_logger("kmc_hardware_driver_observe_node"), "Fatal: %s",
                 e.what());
  }
  rclcpp::shutdown();
  return 0;
}

Result#

examples/Driver_ROS2/src/driver_observe_node.cpp

#include "KMC_driver.hpp"

#include <rclcpp/rclcpp.hpp>
#include <geometry_msgs/msg/twist.hpp>
#include <std_msgs/msg/float32.hpp>

#include <chrono>
#include <optional>
#include <string>

class KmcHardwareDriverObserveNode final : public rclcpp::Node {
public:
  KmcHardwareDriverObserveNode() : Node("kmc_hardware_driver_observe_node") {
    port_ = declare_parameter<std::string>("port", "/dev/ttyKMC");
    baud_ = declare_parameter<int>("baud", 921600);
    control_rate_hz_ = declare_parameter<double>("control_rate_hz", 100.0);
    vehicle_speed_rate_hz_ = declare_parameter<double>("vehicle_speed_rate_hz", 50.0);
    command_timeout_ms_ = declare_parameter<int>("command_timeout_ms", 200);
    command_refresh_hz_ = declare_parameter<double>("command_refresh_hz", 50.0);
    realtime_priority_ = declare_parameter<int>("realtime_priority", -1);
    cpu_affinity_ = declare_parameter<int>("cpu_affinity", -1);
    battery_hz_ = declare_parameter<double>("battery_hz", 1.0);

    KMC_HARDWARE::Driver::Options opt;
    opt.port = port_;
    opt.serial.baudrate = baud_;
    opt.serial.hw_flow_control = true;
    opt.control_rate_hz = control_rate_hz_;
    opt.vehicle_speed_rate_hz = vehicle_speed_rate_hz_;
    opt.command_timeout_ms = command_timeout_ms_;
    opt.realtime_priority = realtime_priority_;
    opt.cpu_affinity = cpu_affinity_;

    opt.poll_battery = battery_hz_ > 0.0;
    opt.battery_rate_hz = battery_hz_ > 0.0 ? battery_hz_ : 1.0;

    if (!driver_.start(opt)) {
      throw std::runtime_error("Failed to open UART port: " + port_);
    }

    speed_pub_ = create_publisher<std_msgs::msg::Float32>("vehicle_speed", 10);
    battery_pub_ = create_publisher<std_msgs::msg::Float32>("battery_voltage", 10);

    cmd_sub_ = create_subscription<geometry_msgs::msg::Twist>(
        "cmd_vel", 10, [this](geometry_msgs::msg::Twist::SharedPtr msg) {
          const float v = static_cast<float>(msg->linear.x);
          const float w = static_cast<float>(msg->angular.z);
          last_cmd_v_ = v;
          last_cmd_w_ = w;
          last_cmd_received_ = now();
          driver_.setCommand(v, w);
        });

    using namespace std::chrono_literals;
    rx_timer_ = create_wall_timer(1ms, [this]() { drainDriverQueue(); });

    if (command_refresh_hz_ > 0.0) {
      const auto period = std::chrono::duration_cast<std::chrono::nanoseconds>(
          std::chrono::duration<double>(1.0 / command_refresh_hz_));
      cmd_timer_ = create_wall_timer(period, [this]() {
        if (!last_cmd_received_.has_value()) return;
        driver_.setCommand(last_cmd_v_, last_cmd_w_);
      });
    }
  }

  ~KmcHardwareDriverObserveNode() override { driver_.stop(); }

private:
  void drainDriverQueue() {
    for (int i = 0; i < 100; ++i) {
      auto msg = driver_.tryPopMessage();
      if (!msg) break;

      if (auto* vs = std::get_if<KMC_HARDWARE::VehicleSpeed>(&*msg)) {
        std_msgs::msg::Float32 out;
        out.data = vs->mps;
        speed_pub_->publish(out);
      } else if (auto* bv = std::get_if<KMC_HARDWARE::BatteryVoltage>(&*msg)) {
        std_msgs::msg::Float32 out;
        out.data = bv->volt;
        battery_pub_->publish(out);
      }
    }
  }

private:
  KMC_HARDWARE::Driver driver_;

  rclcpp::Publisher<std_msgs::msg::Float32>::SharedPtr speed_pub_;
  rclcpp::Publisher<std_msgs::msg::Float32>::SharedPtr battery_pub_;
  rclcpp::Subscription<geometry_msgs::msg::Twist>::SharedPtr cmd_sub_;
  rclcpp::TimerBase::SharedPtr rx_timer_;
  rclcpp::TimerBase::SharedPtr cmd_timer_;

  std::string port_;
  int baud_{921600};
  double control_rate_hz_{100.0};
  double vehicle_speed_rate_hz_{50.0};
  int command_timeout_ms_{200};
  double command_refresh_hz_{50.0};
  int realtime_priority_{-1};
  int cpu_affinity_{-1};
  double battery_hz_{1.0};
  float last_cmd_v_{0.0f};
  float last_cmd_w_{0.0f};
  std::optional<rclcpp::Time> last_cmd_received_;
};

int main(int argc, char** argv) {
  rclcpp::init(argc, argv);
  try {
    auto node = std::make_shared<KmcHardwareDriverObserveNode>();
    rclcpp::spin(node);
  } catch (const std::exception& e) {
    RCLCPP_ERROR(rclcpp::get_logger("kmc_hardware_driver_observe_node"), "Fatal: %s",
                 e.what());
  }
  rclcpp::shutdown();
  return 0;
}

ROS2 Driver Observe

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